Electric ship propulsion system



Feb. 5, 1929. 1,701,373

D. E. JEWITT ELECTRIC SHIP PROPULSION SYSTEM v Filed Sept. 8, 1924 Inventor: Dennis E.Jewitt H is Attorney.

Liu

'CFlUSGFS Patented Feb. 5, 15529.

UNITED STATES .PATENT OFFICE.

DENNIS E. JEWITT, OF RUGBY, ENGLAND ASSIGNOTR- TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTRIC SHIP PROPULSION SYSTEM.

Application filed September 8, 1924, Serial No. 736324, and in Great Britain February 2, 1924.

My invention relates to electric sh p propulsion systems for operating propellers apt to be subject to unequal loads and has for its b ect the provision an improved system thii" character wherein an equal division of the load between the dil 'nt propellers it ljltOlDitillCtlL maintained under different conditions of opeiatioi'i.

In the case of twin screw ships for ample. the division of load between the two propellers varies with the condition of service. Thus it the milder operated to alter the cour of the ship or to con'ipensate tor a side wi one o the propellers is subjected ,1 J Unhalance in the load may also he prodificed by other such as a discrepanqv octwecn the pitches oi the propellers. It is therefore desirable that the relation between the speeds oi the dillercnt propellers be varied to cqualize the propeller loads. In accordance with my invention,- this resu t is accomplished by arrangement in which motor a p coinprisingtwo motors is arranged to drive each propeller shaft and in which each motor oi the dil'li'erc 'zt motor a 'greg'ates is connec' in cascade with a motor n )unted on di ferent propeller shaft. Vvith this arran cmenu. variation from a condition of equal load ion hot n the dillore propellers automatically varies relative of the propeller motors in n to restore equa u crstood 0' description. H1 connon with the accompany ag l us scope will be po nted out appended clainis.

A hows a generator 1 rent to the :u'ovided tor controlling the L enerator l. and t r 'l he secondary to be cc reversing the ship ii desired, or to and for w I a synchronous motor 10 mounted on the shatt of the propeller 4. The secondary winding of the induction motor is linewise v 1 c w ranges to be late connected through a double all throw switch 1L either to the adjustable or to a synchronous motor 13 mounted on the shaft of the propeller 5. EX- citing current may be supplied through the line 1st to the generatorl and also through switch 15 and resistors 16 and 17 respectively to the field windings of the synchronous motors 10 and 13.

The operation of my invention will be readi y understood it it be assumed that the speeds of the propellers d and 5 are initially equal and that the torque of the propeller E tends to increase in value, due to turning oi the ship for example, while that of the propeller l tends to decrease in value. lVhen this occurs, the induction motor 8 runs at a lower speed than the nduc on motor 9 and n ii the rotor current frequency of the motor increased, while that of the motor 2 is decreased due to the fact that its torque is reduced. lnder these conditions, the freo, uenc of the currentsupplied through the induction motor 3 to the synchronous motor the current supspeed and torque of the propeller will be increased and that of the propeller will be decreased u; til the power required to drive the ship is equally divided between the two pro iellers. Likm 'ise, when the torque of the propeller 4 tends to increase and that propeller tends to decrease there is imuiei'liatcly brought into operation a force which eventually equalizes the torques ot the two propellers. My invention thus affords a coupling between the different propellers by which their torques may be automatically maintained at equal values under the dili'crout conditions; of the ships operation.

I have cyplained my invention by illus trating and describing a certain s i" enihodiment thereof, but it will he dcrstood by those skilled in the art that the arrangement of this embodiment may be modified in certain of its details. I, accordingly, do not wish to be restricted to the particular arrangement disclosed herein by way of example for the purpose of setting forth my invention in accordance with the patent statutes. The terms of the appended claims are, therefore not restricted to the precise of said aggregates.

An electric ship propulsion system comprising a plurality of propeller sh its, a plurality of motor aggregates each arranged to a drive a different oneoi said shafts and each comprising induction and synchronous mo tors, and M motor of each aggregate in cascade with a synchronous motor of another aggre 'ate.

3. An alternating current power system comprising plurality of shafts to be driven, a plurality of motor aggregates each arranged to drive a dii'lerent one of said shafts t.

each comprising an induction motor and a synchronous motor, and means tor connectmg the. induction motor of each of sai gregatcs in cascade with" the synchronous motor of another of said aggregates.

in witness whereof, I have hereunto set my hand, this 20th day of August, 192%.

DENNIS E. JEWITT.

means for connecti the induction 

